WO1981001203A1 - Colour analyser - Google Patents

Colour analyser Download PDF

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Publication number
WO1981001203A1
WO1981001203A1 PCT/NL1980/000033 NL8000033W WO8101203A1 WO 1981001203 A1 WO1981001203 A1 WO 1981001203A1 NL 8000033 W NL8000033 W NL 8000033W WO 8101203 A1 WO8101203 A1 WO 8101203A1
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WO
WIPO (PCT)
Prior art keywords
colour
light
analyser
set forth
exposure time
Prior art date
Application number
PCT/NL1980/000033
Other languages
French (fr)
Inventor
H Broersma
Original Assignee
H Broersma
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by H Broersma filed Critical H Broersma
Priority to DE803049990A priority Critical patent/DE3049990A1/en
Publication of WO1981001203A1 publication Critical patent/WO1981001203A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/46—Measurement of colour; Colour measuring devices, e.g. colorimeters
    • G01J3/50—Measurement of colour; Colour measuring devices, e.g. colorimeters using electric radiation detectors
    • G01J3/51—Measurement of colour; Colour measuring devices, e.g. colorimeters using electric radiation detectors using colour filters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R13/00—Arrangements for displaying electric variables or waveforms
    • G01R13/40—Arrangements for displaying electric variables or waveforms using modulation of a light beam otherwise than by mechanical displacement, e.g. by Kerr effect
    • G01R13/404—Arrangements for displaying electric variables or waveforms using modulation of a light beam otherwise than by mechanical displacement, e.g. by Kerr effect for discontinuous display, i.e. display of discrete values
    • G01R13/405—Arrangements for displaying electric variables or waveforms using modulation of a light beam otherwise than by mechanical displacement, e.g. by Kerr effect for discontinuous display, i.e. display of discrete values using a plurality of active, i.e. light emitting, e.g. electro-luminescent elements, i.e. bar graphs
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B27/00—Photographic printing apparatus
    • G03B27/72—Controlling or varying light intensity, spectral composition, or exposure time in photographic printing apparatus
    • G03B27/73—Controlling exposure by variation of spectral composition, e.g. multicolor printers
    • G03B27/735—Controlling exposure by variation of spectral composition, e.g. multicolor printers in dependence upon automatic analysis of the original

Definitions

  • the invention relates to a colour analyser comprising an indicating instrument consisting of three light scales.
  • the princical purpose of the instrument is to presert an indication of a necessary color correction, for colour recording or reproduction purposes.
  • the field of applicat ion comprises, among other things, colour photography and colour television.
  • the embodiment as described is principally designed for use in combination with an enlarger for enlarging colour negatives and transparencies.
  • Such enlargers are usually equipped with three continuously variable colour correction filters.
  • Ihe colour analyser provides a means to determine which correction filters have to be engaged and to what density, to correct for the colour inbalance in tne negative or transparency used.
  • a timedetermining circuit may be added to the analyser, forindieating the correct exposure time for a print or an enlargement .
  • Colour analysers are usually provided with one light sensitive cell. Blue, green and red filters can subsequently be placed in front of this cell, for measuring the respective yellow, magenta and cyan corrections.
  • a suchlike embodiment has been described in U.S. Patent 4,125,550.
  • a disadvantage of this measuring method is the time consuming process of the sequential colour switching and measuring, and also the fact that due to counter absorptions in the correction filters one or two repeated complete measuring cycles are required.
  • Ihese disadvantages are offset in the embodiment of my invention because it is provided with at least three measuring cells, tne signals of these cells being simultaneously transmitted.
  • the colour star thereby exists cf three rows of coloured light sources, such as light emitting diodes, each row in an appropriate colour, and placed under mutual angles of 120 degrees, i.e. as indicated in Fieure 1.
  • the operator can tell which filter knoos to engage at the enlarger, because the analyser indicates them by coloured lights. These coloured lights are extinguished braduaIIy as the operator increases thefilter density, untill all lights are completely darkend w hen the correct density is reached.
  • the indicators may consist of any number of lightsand the indication needs no lineair relation to the corresponding filter density. As it only neeas to show anaccurate zero indication it may minimally comprise only onelight per indication.
  • the colour star is more than a simple system of three indicating instruments . It is actually a single instrument, showing a vetctorial indication of the colour inbalance. Therefor the colour star can only function together with its specially designed signal processor unit. This unit converts the tnree originally measured signals into three other signals, that provide an inmediately recognisable indication for the correction filters needed, if displayed vectcrially.
  • Its four measuring cells 1, 2, 5, and 4 may be either photodiodes or pnotomultipxier tubes.
  • the ceils are provided witn respective blue, green, orange-red, and darkred filters.
  • Sensitive preamplifiers, indicated by 5, 6, 7, and 8 are needed if photodiodes are used, because of tneir lower sensitivity.
  • Switch 9 chooses between the two different red-sensitive cells.
  • the darikred sensitive cell 4 is engaged for enlarging negatives, and the orange-red sensitive cell 3 for transparencies.
  • the three preamplifier signals to be called B, G and R.
  • An analog comparator 15 selects the smallest of the three signals logB . P b . and logG.P g and logR. The selected signal will be termed Smallest log Color.
  • the summing points 16, 17, and 18 substreat the Smallest logColour from the three signals from which it is choosen, resulting in three ne w signals, to be t ermed Y , M, and A t leas t one of las tsaid signals equals zero, becouse it is obtained by sebstracting a ractor from its own value. If i.e.
  • logR issmaller than logB.P b and logG.P g then logR will become Smellest logcolour and the summing point 18 will y iel d asignal equalling zero.
  • cyan correction filtering signalsY and M are then proocrtional to the yellow and magenta correction, Filter densities needed, because they are proportional to the logarithmic density relation of the blue and green components, compared to the red component of the light.
  • Filter densities needed, because they are proportional to the logarithmic density relation of the blue and green components, compared to the red component of the light.
  • the three signals Y, M, and C will automatically become zero. This is clearly demostrated to the operator becouseeach of last said signals is visualised in a proportionallight scale by means of light indicators 23, 24, and 25, which together constitute the colour star.
  • the indicators are controlled by amplifiers 19, 20, and21.
  • a preferred embodiment of my invention also contains an automatic exposure time meter. This will also be described underneath in conjunction with Figure 2.
  • tnat is inversely proportional to the exposing light intensity .
  • signal is directly proportional to the required exposure time.
  • This transition time is then displayed by display unit 23, preferably digital, and controlled by an analog to digital converter 30.
  • This Atod convener is provuded with a hold-switch 3 1, enabling the operator to s tore the exposure time measured at the end of each measurement..
  • the stored signal is transported to a timer 32, engaging relay 34 for the duration of the exposure time, after a start pulse is given with switch 33.
  • a swi tch 35 enables the operator to to switch the enlarger either on,for adjusting and me as uring , or off to allow handling of the photosensitive material in complete darkness.
  • switch 35 Only said las t condition of switch 35 allows relay 34 to switch the enlarger 36 .
  • Power for the enlarger usually from the electric mains, is applied at the power terminals 37.
  • a reciprocity regulator 27, i.e. a switch or potentiometer, is added to the inverter and exponential amplifier 28, allowing, multiplication of the signal logRby a variable factor, ranging at least from 1.0 to 1.2, before the exponent of -logR is taken. Said factor being adjusted to 1.0 results in theexposure time being inver sely proportionnal to the lightintensity, as described before.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectrometry And Color Measurement (AREA)
  • Projection-Type Copiers In General (AREA)

Abstract

A colour analyser measuring the light intensities of at least three different colours within the spectrum of the incident light, and relating these measurements to values programmed before. Those colour components of the incident light that have to be influenced in order to conform to the preprogrammed relations are indicated by means of a colour star, consisting of three rows of light sources (23, 24, 25) of appropriate colours. While influencing the colour of the light with correction filters the operator views the change simultaneously at the colour star. It is indicated in such a way that the light sources of the colour star are extinguished as soon as the preprogrammed relations between the colours are satisfied, notwithstanding the absolute value of the light intensity. An automatic exposure time meter is built in, also controlling an electronic timer (32).

Description

COLOUR ANALYSER
The invention relates to a colour analyser comprising an indicating instrument consisting of three light scales. The princical purpose of the instrument is to presert an indication of a necessary color correction, for colour recording or reproduction purposes. The field of applicat ion comprises, among other things, colour photography and colour television.
The embodiment as described is principally designed for use in combination with an enlarger for enlarging colour negatives and transparencies. Such enlargers are usually equipped with three continuously variable colour correction filters. Ihe colour analyser provides a means to determine which correction filters have to be engaged and to what density, to correct for the colour inbalance in tne negative or transparency used. Besides this, a timedetermining circuit may be added to the analyser, forindieating the correct exposure time for a print or an enlargement .
Colour analysers are usually provided with one light sensitive cell. Blue, green and red filters can subsequently be placed in front of this cell, for measuring the respective yellow, magenta and cyan corrections. A suchlike embodiment has been described in U.S. Patent 4,125,550. A disadvantage of this measuring method is the time consuming process of the sequential colour switching and measuring, and also the fact that due to counter absorptions in the correction filters one or two repeated complete measuring cycles are required.
Ihese disadvantages are offset in the embodiment of my invention because it is provided with at least three measuring cells, tne signals of these cells being simultaneously transmitted.
Another colour analyser with three different cells isknown iron U. S. Patent 3,819,275. A disadvantage of last said analyser, and equally of other known embodiments lies in the necessity to read one or more measuring instruments. The operator is asked to read and interpret three quantities in order to get to a correct filter setting, for every exposure again, with the added difficulty of being in a darkroom. My invention reduces the complicacy of the measurement in a new way, namely by indicating the filters by a lighted colour star, presenting in each case an image of one or two vectors of coloured light, describing the complete colour circle.
The colour star thereby exists cf three rows of coloured light sources, such as light emitting diodes, each row in an appropriate colour, and placed under mutual angles of 120 degrees, i.e. as indicated in Fieure 1.
From one glance the operator can tell which filter knoos to engage at the enlarger, because the analyser indicates them by coloured lights. These coloured lights are extinguished braduaIIy as the operator increases thefilter density, untill all lights are completely darkend w hen the correct density is reached. The indicators may consist of any number of lightsand the indication needs no lineair relation to the corresponding filter density. As it only neeas to show anaccurate zero indication it may minimally comprise only onelight per indication. Hence it follows that the colour star is more than a simple system of three indicating instruments . It is actually a single instrument, showing a vetctorial indication of the colour inbalance. Therefor the colour star can only function together with its specially designed signal processor unit. This unit converts the tnree originally measured signals into three other signals, that provide an inmediately recognisable indication for the correction filters needed, if displayed vectcrially.
The operation of a colour analyser according to my invention will be described hereunder in conjunction with the stock diagram of Figurer 2.
Its four measuring cells 1, 2, 5, and 4 may be either photodiodes or pnotomultipxier tubes. The ceils are provided witn respective blue, green, orange-red, and darkred filters. Sensitive preamplifiers, indicated by 5, 6, 7, and 8 are needed if photodiodes are used, because of tneir lower sensitivity. Switch 9 chooses between the two different red-sensitive cells. The darikred sensitive cell 4 is engaged for enlarging negatives, and the orange-red sensitive cell 3 for transparencies. Thus the color sensitivity of the analyser is changed accordingly to the type of enlarging paper used, as is necessary for accurate results. The three preamplifier signals, to be called B, G and R. respectively, are converted into three signals logB, logG, and logR by logaritnmic amplifiers 10, 11, and 12. Constant voltages logPb and logPg, both adjustable through programmer potentiometers 13 and 14, are added to the signals logB and logG. Said potentiometers are to be programmed ay the operator in such a way that the relation logB.Pb = logG. Pg = logR is satisfied w hen the exposure ofthe measuring cells 1,2,3, and 4 is colour corrected according to the requirments The need for Programming bythe operator is due to differences in the relative coloursensitvities of the three colour dyes of different brandsand tatches of photographic paper, also depending upon the t ypes of developer to be used. For programming the operator nee d s only one test negative of which the correction feltersand exposure time are obtained experimentally, by trial anderror method. An analog comparator 15 selects the smallest of the three signals logB . Pb. and logG.Pg and logR. The selected signal will be termed Smallest log Color. The summing points 16, 17, and 18 substreat the Smallest logColour from the three signals from which it is choosen, resulting in three ne w signals, to be t ermed Y , M, and A t leas t one of las tsaid signals equals zero, becouse it is obtained by sebstracting a ractor from its own value. If i.e. logR issmaller than logB.Pb and logG.Pg then logR will become Smellest logcolour and the summing point 18 will y iel d asignal equalling zero. This means that the red part of the reasured light spectrum is relatyively we aker and so it nee d sno further reduction by cyan correction filtering signalsY and M are then proocrtional to the yellow and magenta correction, Filter densities needed, because they are proportional to the logarithmic density relation of the blue and green components, compared to the red component of the light. As soon as last said filter densities will be applied the three signals Y, M, and C, will automatically become zero. This is clearly demostrated to the operator becouseeach of last said signals is visualised in a proportionallight scale by means of light indicators 23, 24, and 25, which together constitute the colour star. The indicatorsare controlled by amplifiers 19, 20, and21.
A preferred embodiment of my invention also contains an automatic exposure time meter. This will also be described underneath in conjunction with Figure 2.
The same measuring signals of the analyser can beappliea as input signals to the exposure time meter. Aa theanalyser will steadily operate in such a way that at the correct colour balance a fixed realation exists between 3,G, and R, it is sufficient to use only one of the coloursignals, instead of the sum or averge of the three signals.In the described imbodiment signals logR from the logarithmicamplifiesr 12 is used. It is conversed by an inverter and exponential amplifier 28 into a signals 10-logR, Which is equal to
Figure imgf000006_0001
. The operator can influence the proportionalfactor through the sencitivity potentiometer 26. Like potentiometers 13 and 14 also 25 must be ad justed to correct for the specific sensitivities of enlarging paper and developer chemicals.
Many photosensitive materials require an exposure time tnat is inversely proportional to the exposing light intensity . In those cases signal
Figure imgf000006_0002
is directly proportional to the required exposure time. This expusure time is then displayed by display unit 23, preferably digital, and controlled by an analog to digital converter 30. This Atod convener is provuded with a hold-switch 3 1, enabling the operator to s tore the exposure time measured at the end of each measurement.. The stored signal is transported to a timer 32, engaging relay 34 for the duration of the exposure time, after a start pulse is given with switch 33. A swi tch 35 enables the operator to to switch the enlarger either on,for adjusting and me as uring , or off to allow handling of the photosensitive material in complete darkness. Only said las t condition of switch 35 allows relay 34 to switch the enlarger 36 . Power for the enlarger, usually from the electric mains, is applied at the power terminals 37. A reciprocity regulator 27, i.e. a switch or potentiometer, is added to the inverter and exponential amplifier 28, allowing, multiplication of the signal logRby a variable factor, ranging at least from 1.0 to 1.2, before the exponent of -logR is taken. Said factor being adjusted to 1.0 results in theexposure time being inver sely proportionnal to the lightintensity, as described before. Many enlarging papers for color nowever needs a certain added extension of the ex pos ure time in order to maintain e qual dens ity w henlow light intensitied are used. This means that theirsensitivity gradually decreases at lower light intensities.Experiments have shown that an even density can be maintained over an extended range of exposin g time, manely from 2 100 seconds, by adjusting regulator 27to a factor of 1.2.

Claims

What I claim is : 1 . A colo ur analys er c ompros ing at leas t three photoelectric cells , said cells being sensitive to at least three different colours of light, said cells controlling a measuring instrument comprising three light indicators, each of which consists of one or more light sources of an appropriate colour, said light indicators displaying the outcome of the measurement vectorially.
2. A colour analyser as set forth in claim 1 having three light indicators positioned as a star, with mutual angles of 120 degrees.
3. A colour analyser as set forth in claim 1 or 2 comprising electronic circuitry that makes the indication of each light indicator of the colour star directly Proportional to the required colour correction in thecorresponding colour, and zero if the necessary colourcorrection is present.
4. A colour analyser as set forth in claim 3 comprising additional means to select the sensitivity forat least two different wavelengths of red light, corresponding to the sensitive wavelenghts of the cyencoupled dyes in negative image-forming and positive image-forming materials respectively.
5. A colour analyser as set forth in claim 3 comprising additional c irc uitry that convert one or more signals of the analyser automatically into an analog or digital indication of the exposure time.
6. A colour analyser as set forth in claim 5 comprising a memory circuit to store the measured exposure time and a timer to switch an external enlarger on during this exposure time, upon command of the operator.
7. A colour analyser as set from in claim 5 comprising a regulator that enables setting of the quotientof the lof aritnm of the measured light intensity, divededby the logarithm of the calculated exposure time to atleast two defferent values namely 1.0 and 1.2
8. A colour analyser as set forth in one or more of the preceding claims, comprising all other necessary control means, that enable programming of the instrument.
PCT/NL1980/000033 1979-10-19 1980-10-15 Colour analyser WO1981001203A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE803049990A DE3049990A1 (en) 1979-10-19 1980-10-15 Colour analyser

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL7907746 1979-10-19
NL7907746A NL7907746A (en) 1979-10-19 1979-10-19 COLOR ANALYZER.

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WO1981001203A1 true WO1981001203A1 (en) 1981-04-30

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JP (1) JPS56501541A (en)
DE (1) DE3049990A1 (en)
NL (1) NL7907746A (en)
WO (1) WO1981001203A1 (en)

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EP0084636A2 (en) * 1982-01-27 1983-08-03 Durst AG Fabrik Fototechnischer Apparate Process and apparatus for determination of the exposure time

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US5073857A (en) * 1989-06-01 1991-12-17 Accuron Corporation Method and apparatus for cell analysis
US5077806A (en) * 1989-06-01 1991-12-31 Accuron Corporation Machine vision analysis apparatus
US5117101A (en) * 1990-08-13 1992-05-26 Technostics Corporation Tristimulus color recognition system with means for compensating for variations in light source color
US5766006A (en) * 1995-06-26 1998-06-16 Murljacic; Maryann Lehmann Tooth shade analyzer system and methods
JP4230113B2 (en) * 1998-11-03 2009-02-25 シェード アナライジング テクノロジーズ インコーポレイテッド Interactive dental treatment network
US8790118B2 (en) * 1998-11-03 2014-07-29 Shade Analyzing Technologies, Inc. Interactive dental restorative network
ATE439646T1 (en) 1998-11-03 2009-08-15 Shade Analyzing Technologies Inc SYSTEM AND METHOD FOR ANALYZING THE COLOR NUANCES OF TEETH
US6567159B1 (en) * 1999-10-13 2003-05-20 Gaming Analysis, Inc. System for recognizing a gaming chip and method of use
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US7118374B2 (en) 2003-06-09 2006-10-10 Ivoclar Vivadent Ag Enhanced tooth shade guide
US7341450B2 (en) * 2003-10-03 2008-03-11 Shade Analyzing Technologies, Inc. Tooth shade scan system and method
US20050112522A1 (en) * 2003-11-26 2005-05-26 Riley Mary F. Method for selecting color for a dental prosthesis
US7351245B2 (en) * 2004-09-21 2008-04-01 Bernice Joy Rozinsky Apparatus and method for dislodging object from throat

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CH531760A (en) * 1970-09-08 1972-12-15 Franz Dr Gelder Device for the optical representation of business variables
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DE2409909A1 (en) * 1974-03-01 1975-09-11 Polygram Gmbh Phase difference indicator for stereo channesl - line of elements illuminated to length indicating phase difference
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EP0084636A3 (en) * 1982-01-27 1983-08-10 Durst Ag Fabrik Fototechnischer Apparate Process and apparatus for determination of the exposure time

Also Published As

Publication number Publication date
JPS56501541A (en) 1981-10-22
DE3049990A1 (en) 1982-03-18
US4518258A (en) 1985-05-21
NL7907746A (en) 1981-04-22

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